[Call for Suggestions] Monsters

On the topic of Liches (and by extension Death Knights), I've been interested in a similar concept in the form of a Wraith-like entity who was once a cleric that has been (willingly, or unwillingly) cursed/ forsaken by their deity for an unforgivable/ extreme sin (e.g., hubris, treachery, heresy, blasphemy), and are now bound to an unholy symbol (or something similar). 

Redbeard

War pixies and sprites on dragonflies. Give them leaders, warriors, sergeants etc. Dragonflies should have armor.

Some god stats? Like Asmodius or Bahamut etc.?

Perhaps something along the lines of a true shadow creature. One that forms out of the shadows and can even retreat/evade back into them. It would have no real features only the outline of a shape, maybe the shape of the opponents greatest fear or even a replica shape of the character, but no actual features (face, skin tone, clothing, etc). Of course it would have Devils Sight or something similar as it would be immune to the darkness spell. Attacks and impacts would probably be more mental and psychological, but could still do physical damage. ... Just a thought. :)

How about building out character-like NPCs as potential nemeses for player characters?

A sentient rainstorm or snowstorm that can track and gradually wear down a party. It feeds on exhaustion and causes levels of exhaustion on successful hits. Can appear or disappear at will. If anyone is killed they are raised as some sort of barely corporeal undead that follows the storm and makes wailing noises - perhaps a sanity check against the wails to avoid psychic damage.

Rhino humanoid druid

Dr The Eliminator

More illithid ceremorphosis suggestions. Things to make an more complete eldritch campaign such as illithid sahuagin, giants, tarrasque etc. Maybe ceremorphosis player races such as tabaxi, aarakocra or even genasi? If this is too close to your point 3 some monstrous creatures of the depths for a more varied at sea campaign.

Andy C

I called the witch-doctor he told me what to do, I called the witch doctor he taught me what to say...

Gravy

A fetcher?

Gravy

Personally I enjoy creative and unique creatures that are a mashup of two irl creatures (ex. owlbear, or bat-lemur). I would like to see a few more of these. Suggestions: red panda + corgi, butterfly + duck, ettin + crab (like a centaur, but crab instead of horsy), firefly + weeping willow, penguin + ostrich, etc.

Gravy

Hi, my DM friends and I think there aren't enough Liches in the game :'). We were thinking about a Mayan Lich who uses sacrifices (not just human) to harvest power for himself and its phylactery, which could be the sacrificial altar itself. So, something on the lines of a necromancer which could have different stages and abilities, as to make the CR variable.!

What about somthing that looks like a dog but with no eyes and they only go towards someone using magic. I would like to call them essent seeker. But if not thats fine.

I have an idea for a trap monster inspired by that 80’s movie The Gate Wall Terror (medium undead) Occasionally, some people are killed and, for one reason or another, stuffed into a hollow wall. Should negative energy or necromantic magic touch this wall, a Wall Terror is born. The soul, furious about its unceremonious burial, will reach out of the wall at anyone in 5 feet of them and pull others into the wall as well. Necromancers and mad sorcerers have learned of this and used it to set traps on unsuspecting thieves or adventurers infiltrating their lair.

Kyle A. Berg